Pool Volume Chart (Gallons by Size)
Pool volume charts showing US gallons by size: a rectangular grid by length and width at common average depths, plus round pool gallons by diameter and depth.
Quick answer: Rectangular pool gallons = length x width x average depth x 7.48. Round pool gallons = diameter x diameter x average depth x 5.9. A 16 by 32 pool at 5 feet holds about 19,100 gallons; a 12 by 24 at 4.5 feet holds about 9,700 gallons; a 24-foot round at 4.5 feet holds about 15,300 gallons. Use the grids below to read your size and depth directly.
This page puts the two formulas to work so you can read your pool's gallons straight off a grid. Find your dimensions, pick your average depth column, and you have the number that drives every chemical dose. For an exact figure on an odd-shaped pool, run it through the pool volume calculator.
Rectangular pool volume by size and depth (US gallons)
Columns are average depth in feet (shallow plus deep, divided by two). Figures are rounded to the nearest hundred.
| Size (ft) | 4 ft avg | 4.5 ft avg | 5 ft avg | 5.5 ft avg |
|---|---|---|---|---|
| 10 x 20 | 5,980 | 6,730 | 7,480 | 8,230 |
| 12 x 24 | 8,600 | 9,700 | 10,800 | 11,800 |
| 14 x 28 | 11,700 | 13,200 | 14,700 | 16,100 |
| 15 x 30 | 13,500 | 15,100 | 16,800 | 18,500 |
| 16 x 32 | 15,300 | 17,200 | 19,100 | 21,100 |
| 18 x 36 | 19,400 | 21,800 | 24,200 | 26,700 |
| 20 x 40 | 23,900 | 26,900 | 29,900 | 32,900 |
Round pool volume by diameter and depth (US gallons)
Above-ground round pools are usually filled to the skimmer, giving a working water depth near 4 feet for a 52-inch wall and about 3.5 feet for a 48-inch wall.
| Diameter (ft) | 4 ft depth | 4.5 ft depth | 5 ft depth |
|---|---|---|---|
| 12 ft round | 3,400 | 3,800 | 4,250 |
| 15 ft round | 5,300 | 6,000 | 6,600 |
| 18 ft round | 7,600 | 8,600 | 9,600 |
| 21 ft round | 10,400 | 11,700 | 13,000 |
| 24 ft round | 13,600 | 15,300 | 17,000 |
| 27 ft round | 17,200 | 19,400 | 21,500 |
| 30 ft round | 21,200 | 23,900 | 26,600 |
How to read the charts
Find your length-by-width row (or diameter row for a round pool), then slide across to the column that matches your average depth. The cell where they meet is your volume in US gallons. If your depth falls between two columns, take the midpoint of the two cells.
Getting average depth right
Average depth is the most common place people go wrong. For a pool with a shallow and a deep end, add the two depths and divide by two. A constant-depth pool, like most above-ground pools, simply uses its water depth. Remember that you fill to the skimmer, not the rim, so an above-ground pool's water depth is several inches less than its wall height.
Shapes that are not rectangles or circles
For an oval pool, multiply long diameter by short diameter by average depth by 5.9, just like a round pool. For freeform, kidney, and lagoon pools, estimate average length and width, calculate as a rectangle, then multiply by about 0.85 to account for the curves. Our calculator builds these shape factors in.
Put your gallons to work
Once you have your number, it powers everything else. Use it with the chlorine calculator for daily dosing, the salt calculator for a saltwater pool, and the pH and alkalinity calculator for balancing. For chemistry targets at a glance, see the pool chemistry levels chart.
Have an unusual size or shape? The pool volume calculator gives an exact gallon figure for rectangular, round, oval, and freeform pools in a few seconds.
Frequently Asked Questions
How do I calculate pool volume in gallons?
For a rectangular pool, multiply length times width times average depth in feet, then multiply by 7.48 gallons per cubic foot. For a round pool, multiply diameter times diameter times average depth times 5.9. Average depth is the shallow end plus the deep end divided by two. The grids on this page do the multiplication for you across the most common pool sizes and depths.
What is the 7.48 multiplier in the formula?
There are 7.48 US gallons in one cubic foot of water. So once you know your pool volume in cubic feet (length times width times average depth), multiplying by 7.48 converts it straight to gallons. For round pools, the 5.9 multiplier already combines the circle-area constant with the 7.48 conversion, so you skip a step.
Why use average depth instead of the deepest point?
Most pools slope from a shallow end to a deep end, so only part of the pool is at maximum depth. Using the deep-end number would badly overstate your gallons. Average depth, the shallow plus deep divided by two, represents the whole pool fairly. A pool that runs 3 to 8 feet has a 5.5-foot average, not 8.
How do I handle an oval or freeform pool?
For an oval pool, use long diameter times short diameter times average depth times 5.9. For a freeform, kidney, or lagoon shape, estimate an average length and average width, calculate it as a rectangle, then multiply by about 0.85 to trim the curved corners. That lands you within a few percent, which is accurate enough for dosing chemicals.
Does water temperature change pool volume?
Not in any way that matters for pool care. Water expands a fraction of a percent across normal pool temperatures, far too little to affect chemical dosing. Use a single gallon figure based on your dimensions year-round. The bigger source of error is misjudging average depth or filling an above-ground pool only to the skimmer.
How precise does my gallon figure need to be?
Within a few hundred gallons is plenty, because you always test and retest after dosing. The goal is to avoid large errors, like treating a 30,000-gallon pool as 15,000. Measure your real dimensions once, pick the closest cell in these charts, write the number down, and reuse it for every calculation.
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